I wrote software to make a destination folder match a source folder, deleting extra files from the destination. Files with the same timestamp and size are skipped. It goes real fast and I use it for many purposes. What I also do is backup an entire windows C: drive by booting to a second partition. To do this a drive letter is mapped to a path for that machine on a shared folder, and because a drive letter is used the length of source and destination paths are the same. Unfortunately I cannot easily backup the drive containing all the backups. This is because many of the paths exceed the 260 character limit.
I would like to find software that doesn't have this limitation and functions similar to what is described here.